756 AQUATIC PHYCOMYCETES 



Rhizidiomyces hirsutus Karling 

 Bull. Torrey Bot. Club, 72: 47, figs. 1-19. 1945 



Sporangium extramatrical, nonapophysate, hyaline, globose (6-180 ;x 

 in diameter), oval (8-20 26-60 jx), pyriform, obpyriform, oblong or 

 irregular, provided with 3-47 coarse elongate setae 15-190 jx long by 

 2-3 fx wide; rhizoidal system in solid substratum much branched, arising 

 mostly from a single axis at the base of the sporangium, in liquid media 

 lacking, or composed of several radiating axes from which arise branch- 

 ed rhizoids; zoospores oval, oblong or elongate, 3-4 x 6-8 tx, with a 

 single minute refringent granule and a flagellum 14-18 jx long; resting 

 spore not observed. 



On hempseed bait, leaf mold, Karling (he. cit.), Brazil; pollen of 

 Cucurbita sp. (Michigan), United States. 



As in Rhizidiomyces hansonii, Karling could not demonstrate a ves- 

 icle around the developing spore mass. Sometimes in liquid culture no 

 rhizoidal system was produced, only setae. These were supposed to 

 function as absorbing organs. The formation of abundant setae on the 

 sporangia renders this a highly characteristic species. The Michigan 

 material was densely covered with setae, which were sometimes 

 branched. 



Rhizidiomyces ichneumon Gobi 



Scripta Bot. Horti Univ. Imper. Petro., 15:251, pi. 6, figs. 1-28, pi. 7, figs.29-39. 



1900 



Sporangium consisting of two intercommunicating parts, an epibiotic 

 sessile spherical or rarely flattened portion 9-16 u. high, with a smooth 

 thin colorless wall which collapses after zoospore discharge and a more 

 or less elongate apical discharge tube, and (in previously uninfected 

 host cells) a smaller endobiotic spherical, rarely pyriform or fusiform, 

 portion 3-5 (x high, from the base of which emerges a system of delicate 

 falsely dichotomously branched rhizoids ; zoospores formed by progres- 

 sive cleavage in an evanescent vesicle, from four to sixty, subspherical 

 or ovoid, about 3 jx long, with fine or coarsely granular plasma and an 

 anterior flagellum, movement slow and even. 



Parasitic on actively moving and encysted Chlamydomonas globulosa, 

 Russia. 



